ICSD Help (Close)

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Example searches :

• Elements = Cu O (Any number of Cu and O atoms in the sum formula).
• Elements = Y Ba2 Cu3 O (Specific numbers of 2 Ba and 3 Cu atoms in the SUM formula).
• Elements = Zn "P2 O7" (Zn plus a specific formula unit "P2 O7" in the structure formula).
• Elements = Cu O , Title = supercond
• Authors = Ahtee Hewat
• Authors = Hewat , Years = 1987-1997 , Elements = Y Ba2 Cu , Element Count = 3-5
• Years = 1900-2100 (The total number of database entries).

Notes :

Start by filling in only 2 or 3 boxes. If the number of results is too large, fill in more boxes.

If your search is too specific, you may miss relevent entries.

The most useful searches are on 'Elements', 'Element Count', 'Authors', 'Title', ...

Once the compounds of interest are defined, searches on symmetry, coordination etc can be tried.

Clicking the ANX, Pearson or Wyckoff symbol in a Results box is a powerful way of finding similar structures.

Note the difference between structure formula, and sum formula containing totals for each element.

Note that exact matches are required for "quoted strings", so be careful with the use of quotes.

Note that an SQL underscore _ means "any single character" and % means "any string of characters".

Click on the Struct.Formula to draw the structure using Jmol (Java enabled browsers)
Select up to 4 entries and click the Jmol button to compare their structures.

The Action Buttons:

Before clicking the following action buttons, select at least one entry found after a search.

• References: List the corresponding publications; multiple references refer to earlier papers.
• Endnote: Exports entries in the Endnote personal reference database format.
• Details: List the structure details. Choose two (or more) to compare. Choose one for full details.
• CIF: Exports the entry in IUCr CIF format. Available under "Details" of a single entry.
• Bonds: Calculates bond lengths and angles between specified atom pairs.
• Pattern: Produces a PDF or postscript drawing of the X-ray or neutron powder diffraction pattern.
• Structure: Produces a VRML or PDB 3D-drawing of the crystal structure.
• Jmol: Produces a Jmol 3D-drawing of the crystal structure. Select up to 4 entries to compare their structures.

ICSD Help : Authors/Code (Close)

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The names of the authors or else the "Collection Code" number of the ICSD entry.

Example Authors/Code search :

• simon, (An author name, terminated preferably by a comma)
• Kuz'ma,
• "Simon, A"
• "Simon, " not "Simon, A" (any other Simon eg: Simon, F.; Meyer-Simon, E.; Simon, B.; Simon, G.L.)
• Simon, and "von Benda,"
• Simon, or "von Benda,"
• Simon, not "von Benda,"
• "le Bail," or leBail, (spelling? Le Bail, or leBail, )
• Kolod ziejczyk, (spelling? Kolodziejczyk, or Kolodzierjczyk, )
• "von G__rtner," (spelling? von Gaertner, )
• 66894 (A unique ICSD "Collection Code" number)
• 66894 66903 (A series of code numbers)
• 66894-66903 or 66894 to 66903 (A range of code numbers)

Notes :

• Searches are case insensitive (ex : Simon, = simon, ).
• Delimit the author name with a comma (ex : Simon, ).
• If you don't know the exact spelling, replace unknown letters by a space or an exact number of underscores.

ICSD Help : Years (Close)

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This is the year of publication.

Example Years search :

• 1985
• 1995 2002
• 1995 or 2002
• 1995 to 1998
• 1995-1998
• 1976-1980 or 1974
• 1970 1984-1986 1975
• 1913-2010 (All database entries)

Notes :

• ICSD contains entries from 1913.

ICSD Help : Journal (Close)

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The journal CODEN or part of the journal NAME.

Example Journal :

• ACACBN
• Acta Cryst
• Amer Chem Soc

Notes :

• Journal searches use the international 6-character CODEN (eg ACACBN for Acta Cryst A).
• Else enter an abreviation of the journal name to search for journals containing those strings.
• Most articles are found in about 80 main journals but many other journals are also searched.
• The PDF number is best searched for in the Remarks box.

ICSD Help : Title (Close)

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All of the words or parts of words entered here must be found in either the Title or Comments fields

Example Title or Comment search :

• HT-form (Comment : High Temperature form).
• PDF 36-1451 (Comment : Powder Diffraction File 36-1451).
• super
• superstruct
• supercond oxide

Notes :

• The search is conducted on both the Title and the Comments fields.
• Strings like 'super' will return any title or comment that contains *super*.
• The PDF number is often in the comments field, but it is best entered in the Remarks box.

ICSD Help : Elements (Close)

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This is just a list of some of the elements in the cell. You can follow the element symbol by a number to indicate the total number of atoms of that particular element. You may want to specify also the "Element Count", the total number of different elements. The default logic is AND but you can also use explicitly OR and NOT.
New! Element Groups can now be used (see the Notes).

Example Elements search :(Enter the element symbols or choose from the Periodic Table).

• Cu O (Any material containing Cu and O).
• Cu O with 2 elements (All copper oxides).
• Cu (O or Cl) (Any material containing Cu and either O or Cl).
• Cu O or Cl (Wrong! This gives all materials containing Cl; parentheses are needed here).
• Cu O not Cl (Any material containing Cu and O but not Cl; parentheses are NOT needed here).
• Cu not (O or Cl4) (Wrong! Instead use Cu not O not Cl4 Avoid parentheses when possible).
• Y Ba2 Cu3 O (Elements Y and O with a total of 2 atoms of Ba and 3 of Cu).
• Zn "P2 O7" (Zn plus a specific formula unit "P2 O7" in the structure formula).
• Cu2.1to2.2 O (Copper oxides with Cu content between 2.1to2.2 NB no spaces!).
• O Cu+2.5 (Oxides with Cu oxidation state +2.5).
• O (Cu+2.5 or Ni+2.5) (Oxides with either Cu or Ni +2.5 OR is slow without year, author...).
• Y O-2 Cu+2.4to2.6 (Y-Oxides with oxidation states O-2 & Cu+2.4to2.6 NB no spaces!).
• CRG O with 2 elements (Binary oxides of the Chromium group).
• MET O3 with 2 elements (Binary metal tri-oxides. Note: MET2 O3 is not permitted - see the Notes).
• NOM O with 2 elements (Wrong! Oxygen is itself a NOn-Metal Instead use NOT MET O with 2 elements).

Notes :

• If the number of atoms is specified eg Cu3, this refers to the TOTAL number of atoms of this element.
• The 'Element Count' is useful with 'Element' searches, but remember that impurities are included.
• "ORs" and range searches are slow; put them last in the list of elements to search.
• Use additional criteria (authors, years...) for slow searches (ranges of oxidation, stoichiometry etc).
• If you use multiple "ORs" especially, restrict the search using additional criteria (authors, years...).
• You cannot use stoichiometry or valence qualifiers with group searches. ie "OG" is OK but NOT "OG2"

ICSD Help : Element Count (Close)

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The "Element Count" is simply the number of different elements in the material
eg in MnNa(H2PO3)3(H2O) There are 5 different elements (Ca,Si,O,F,H).

Example Element Count or Chemical Name:

• 2
• 5-7
• 5 to 7

Notes :

• The 'Element Count' is useful with 'Element' searches, but remember that impurities are included.

ICSD Help : Chemical Name, Mineral Name, or Mineral Group (Close)

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An unqualified name string will be assumed by default to be a mineral name.

• alumina (Any mineral name containing the string "alumina").

Otherwise, C= or M= or G= must be specified as below.

Example: C=Chemical Name

• C=alumina(Any chemical name containing the string "alumina").
• C=dihydrogenphosphate (The string "dihydrogenphosphate" in the chemical name).
• C=dihydrogen phosphate (The two strings "dihydrogen" and "phosphate" in the chemical name).
• C="dihydrogen phosphate" (The exact string "dihydrogen phosphate" in the chemical name).

Example M=Mineral Name or G=Group Name :

• M=apatite (Any mineral name containing the string "apatite")
• M=fl apatite (spaces replace uncertain letters).
• M=perovskite (The mineral Perovskite).
• G=perovskite (The perovskite GROUP contains many more examples).
• G=perovskite OR silicate (Minerals belonging to GROUPS perovskite OR silicate).
• M=zeolite OR sodalite (Minerals zeolite OR sodalite).
• M=zeo Y (zeolite Y but also any zeolite with a Y in its name!)
• M="zeolite Y" ("zeolite Y" as a string)
• M=_ (all minerals)

Notes :

• The chemical/mineral name string(s) include every occurance. 'zeo Y' means '*zeo* and Y' including Zeophyllite.
• Try searching for Si O with 2 elements and zeolite, display the structure then click on the 'cavities' button.

ICSD Help : ANX Formula, Pearson Symbol or Structure Type (Close)

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An unqualified string will be assumed to be an ANX formula.

• ABX6 (All ANX formulae are searched for the string "ABX6").

Otherwise, A= or P= or T= must be specified as below.

The ANX formula : Elements with a positive oxidation state are labelled by the first letters of the alphabet (A-M), elements with a negative oxidation state are labelled by the last letters (X-Z, W, V, U, T, S), while elements with oxidation state 0 are labelled by the letters N-R.

• The ANX formula is only calculated for fully determined structures.
• Hydrogen and its isotopes, when they occur in the positive oxidation state, are disregarded.
• If an element in the structure occurs in various oxidation states, this is indicated by different letters.
• Within a group of letters, the letters are arranged according to increasing indices.
• In the case of a defect structure, a partial site occupation is disregarded.
• In mixed crystals, atoms in identical positions are labelled by the letter of the most frequent element.
• If there is doubt about the oxidation state, the use of the ANX formula requires careful consideration.
  (e.g. K Fe (Fe (C N)6), Ca B6, N4 S4 H4, Hg Pb P14, Cs B9 H14, ...).

Example ANX formula :

Ca2 Si O4 : A=AB2X4	H2 O : A=X
Ca S O4 (H 2 O)2 : A=ABX6	Ca H2 : A=AX2
(Na0.2 K0.8) (Al Si3) O8 : A=AB4X8	Fe3 O4 : A=AB2X4
Na Tl : A=NO	Na2 S2 O3 : A=ABX2Y3

• Note that AB2X will also find AB2X2 etc. Better to give "AB2X" or include the space group number.

The Pearson Symbol consists of :

• One letter for the crystal system : A, M, O, T, H or C (Asym/Triclinic, Mono, Ortho, Tet, Hex or Cubic).
• One letter for the Bravais lattice : P, C, F, I or R (Primitive, C-centered, F-centered, I-centered, Rhomb.).
• The total number of atoms in the unit cell.
• Note that P=MP4 will also find P=MP40 etc. Better to give P="MP4" or include space group number.

Example Pearson Symbols :

• P=TI12 : Tetragonal, I-centered cell containing 12 atoms (Anatase TiO2-type).
• P=MP4, space group=11 : Monoclinic, P-centered cell with 4 atoms and space group 11 (NiTi-type).
• P=F : Any F-centered unit cell.

The Structure Type:

The Structure Type as defined by Prof. R. Allmann (Marburg) depends on the Space Group, Pearson Symbol and Wyckoff Sequence, all of which can otherwise be searched for seperately in ICSD. In a few cases the c/a ratio is used. Allmann Structure Types are at present only defined for cubic and tetragonal materials.

Example Structure Types :

• T=AuCu3 (L1(2)-type, if disordered: Cu-type).
• T=CaTiO3 (E2(1)-type).

Note that including the Structure Type in quotes eg T="AuCu3" will ensure that only "AuCu3" will be found.

ICSD Help : System (Close)

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The crystal system is a rough classification of over-all crystal symmetry. Be careful in using it, since the real symmetry of many compounds is often lower than first determined.

ICSD Help : Laue Class (Close)

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Be careful in using the Laue Class symmetry, since the real symmetry of many compounds is often lower than first determined.

ICSD Help : Centering (Close)

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Space groups can be classed as having a center of symmetry (Centered) or Non-Centered; many non-centered cells are are also Polar.

ICSD Help : Space Group (Close)

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You can select a particular space group from the Space Group Table. Example Space Group :

• P4 : Space Group starts with P and contains 4 ie any of P4, P4-, P41 etc.
• "P4" : Space Group is an exact match to "P4" (quotes required).
• "C2/c" : This won't work; remove the quotes and use C2/c or quote the full symbol "C12/c1".
• C2/c : Space group starts with C and contains 2/c.
• Cmca : Space group starts with C and contains mca with the mca setting.
• 64 : Space group 64 (Cmca) with any setting.
• Cmca or Cmcm : Space group starts with C and contains mca OR starts with C and contains mcm.
• "Cmca" or "Cmcm" : Space group is an exact match to either Cmca or Cmcm
• 64 or 63 : Space group is either 64 or 63, with any setting.
• F : Space group starts with F ie any F-centered space group.

Notes :

• A "Z" following the SG symbol means the coordinate origin is at the centre (Zentrum). An "S" means not.
• Centrosymmetric structures with a different coordinate origin ("S") are not suitable for most applications.
• Jeremy Cockcroft has constructed an HTML version of the Space Group Tables
• The Bilbao Crystallographic Server contains tools for exploring group-subgroup relations.
• The Space Group Frequency Table lists the frequency of all 230 space groups in ICSD up to year 2005

ICSD Help : Cell Size (Close)

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The unit cell volume v, density d, molecular mass m, cell dimensions a, b, c, angles al, be, ga
or c/a ratio. The default search is on cell volume.

Example Cell Size :

• 950-960 (volume between 950 to 960 ų)
• 950 to 960
• v=950-960
• d=3.5-3.6 (density between 3.5 to 3.6 gm/cm³)
• m=700-720 (molecular mass between 700 to 720)
• c=9.6-9.7 (c dimension between 9.6 to 9.7 Å)
• be=89.90-89.99 (Beta angle between 89.90 to 89.99^o)
• c/a=1.95-2.0 (c/a lattice ratio between 1.95 and 2.0)
• a=9.0-10.0 c/a=1.95-2.0 (a between 9 to 10 and c/a lbetween 1.95 and 2.0)

Notes :

• Although you can give a single number, you should always specify a range of cell dimensions.
• The given range should not be too small; dimensions are stored in rather large increments.

ICSD Help : Wyckoff Sequence (Close)

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The Wyckoff Sequence is a (partial) list of Wyckoff positions 2a, 4b etc. You cannot search for an exact string. When combined with the Space Group it is a powerful means of finding similar structures. If it is used as the only criterium, searching can be long, so combine it with other criteria as below.

Example Wyckoff Sequence :

• 2e 2a (The symbols 2e and 2a are found in the Wyckoff sequence in any order).
• 2t 1h 1a 2q 2s 2r 1e (all structures similar to the YBa2Cu3O7 superconductor).
• Pmmm & Wyckoff=2t 1h 1a 2q 2s 2r 1e (for a faster search).
• Cu O & Wyckoff=2t 1h 1a 2q 2s 2r 1e (also faster).
• Cu O & Wyckoff=2t 1h 1a 2q 2s 2r 2k (similar structures but O4 displaced from the y-axis 1e position).
• Cu O & Wyckoff=2t 1h 1a 2q 2s 2r (similar structures containing either 1e or 2k or other positions).

The Wyckoff Symbol is a different classification based on the number of distinct a,b,c etc positions. eg "e11" means 11 distinct e-positions. You must search on an exact substring of the Wyckoff Symbol, but to this you can add individual Wyckoff positions.

Example Wyckoff Symbol :

• "e11 c" (The Wyckoff Symbol contains the exact string "e11 c").
• "e11" c (The Wyckoff Symbol contains "e11" and there are atoms at Wyckoff positions c in any order).

Note: Wyckoff Symbols are listed with the structure Details, where you can search for other structures with the same symbol.

ICSD Help : Remarks (Close)

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This search is conducted on both the Remarks and Tests fields.

• Remarks contain information about experimental conditions.
• Tests can indicate problems with the reported structure.

Example Remark or Test Codes (see the lists below) :

• XDC : X-ray Diffraction from Crystals.
• XDP : X-ray Diffraction from Powders.
• NDP : Neutron Diffraction from Powders.
• RVP : Rietveld Profile Refinement.
• MIN apa : MINeral name contains apa eg apatite.
• PDF 32-77 (PDF number contains 32-77)
• TEM 29 : TEMperature contains 29 ie 290-299.
• PRE : PREssure reported (various units are used, so don't search on the value.
• DIS oxygen : DISordered oxygen.
• t74 : Test code t74 : Coordinates are those given in the paper but are obviously wrong. (see list below).
• AHT Uij : Anisotropic temperature factors Uij (or Bij or Betaij can also be specified).
• NOT AHT : Isotropic temperature factors, or no temperature factors

List of Remark Codes :

ABC  : Absolute Configuration given.
AHT  : Anharmonic temperature factors given (attention: 1/3 of all structures).
CGD  : The structure contains atom groups whose centre of gravity only has been determined.
COA  : Published data has been corrected through correspondence with the author.
COR  : This publication corrects errors in an earlier one.
DEF  : Defect structure. At least one site occupation is less than one in total.
DIS  : Disordered structure that cannot adequately be described by numerical parameters.
EDP  : Electron diffraction (powder).
EDS  : Electron diffraction (single crystal).
EMP  : Electron Microscopy (powder).
ESC  : Electron structure calculation.
MAG  : Magnetic structure also determined.
MIN  : Compound with mineral name.
MOD  : Modulated structure.
MXD  : Mixed Valence compound.
NDP  : Neutron diffraction (powder).
NDS  : Neutron diffraction (single crystal).
NMR  : NMR-spectroscopy data given.
ODS  : Order-disorder structure.
PDC  : The structure has been assigned a PDC number.
PDF  : The structure has been assigned a PDF number.
POL  : Polytype structure.
PRC  : Preliminary publication.
PRE  : Pressure at which the structure was determined (in MPa or units as given).
REF  : New refinement basing on previously measured intensities.
RVP  : Rietveld Profile Refinement applied.
SFP  : Structure determined from projections.
SNP  : Synchroton radiation (powder).
SNS  : Synchroton radiation (single crystal).
TEM  : Temperature in Kelvin at which the determination was made (if not room temperature).
THE  : Structure calculated theoretically.
TWI  : Structure determination from a twinned crystal.
TYP  : Structure type specified (use instead the ANX/Pearson/S.Type search).
XDP  : X-ray diffraction (powder).
XDS  : X-ray diffraction (single crystal).

List of Test Codes :

t21  : Difference between the formula calculated from the PARM record and the FORM record tolerable.
t22  : Deviation of the charge sum from zero tolerable.
t23  : Calculated density unusual but tolerable.
t51  : No R value given in the paper.
t52  : At least one temperature factor is implausible or meaningless but agrees with the value given in the paper.
t53  : At least one temperature factor missing in the paper.
t54  : A site occupation is implausible or meaningless but agrees with the paper.
t55  : The lattice Parameters are unusual but agree with the paper.
t56  : The paper reports the temperature factors in a non-standard way and they are not included in the entry.
t73  : Coordinates not determined but the structure type is given.
t74  : Coordinates are those given in the paper but are obviously wrong.
t75  : The coordinates given in the paper contain an error. The values in the database have been corrected.
t76  : The coordinates are those given in the paper but the atomic distances do not agree with those calculated during testing. The coordinates are probably correct.

ICSD Help : Minimum Distance (Close)

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Example Minimal Distance :

• Cu-O=1.5 : the shortest distance between a Cu and O atom does not exceed 1.5A
• Cu-O=1.5-1.7 : the shortest distance between a Cu and O atom is between 1.5A and 1.7A
• Cu-O=1.5to1.7 : the shortest distance between a Cu and O atom is between 1.5A and 1.7A

Notes :

• This means only the shortest distance between the atoms of the specified kind.
• The minimal distance specification is interpreted as a range from 0 up to the specified distance.
• A range like Cu-O=1.5-1.7 does not find compounds with bonds in that range and also shorter bonds.
• For distances that lie within a precisely defined interval the Distance Select criterium is more powerful.

ICSD Help : Distance Select (Close)

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Warning : "Distance Select" field not used in search yet !

The pairs of atoms between which distance calculations are to be made according to the optional Distance Range and/or Co-ordination number. If only one atom name is given, all other types of bonded atom are considered. If a list of atom names is given eg Cu,Al then all from this list are considered. Example Distance Select :

• Cu-O
• Cu to O
• Cu O
• ALL-O
• Cu

Notes :

• You must use explicit element names, not element-group names such as TRM. Instead use the generic name ALL. Eg search for Elements "TRM N H not C not O" and then Distance Select ALL-N.
• The Distance Select operation requires a relatively large amount of computing time, as the whole of the current subset has to be examined. Distance Selection should be accelerated by reducing the number of entries to be calculated using other selection criteria; in particular either the Min. Distance or Distance Range criteria are required as well.

ICSD Help : Distance Range (Close)

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Warning : "Distance Range" field not used in search yet !

The range of distances to be considered for the Distance Select atom pairs (also required).

Example Distance Range :

• 1.8-2.2
• 1.8 to 2.2
• 1.15*IR : Distances up to 1.5 times the sum of the Ionic Radii.

Notes :

• The distance range can either be in absolute values (Angstrom units) or relative to the ionic radii IR. In this case, the specification consists of a tolerance factor followed by "*IR". The tolerance factor is >1 or <1 depending on whether maximum or minimum distances are to be selected.
• Maximum distance : 1.15*IR means that a distance between an atom A and any other atom X will only be selected if it is less than 1.15*(ionic radius(A)+ionic radius(X)).
• Minimum distance : 0.9*IR means that a distance between an atom A and any other atom X will only be selected if it is greater than 0.9*(ionic radius(A)+ionic radius(X)).
• Dist.Select should be accelerated by reducing the number of entries to be calculated using other selection criteria, and in particular the Min.Distance criterium.

ICSD Help : Co-ordination (Close)

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Warning : "Co-ordination" field not used in search yet !

Example Coordination Numbers :

• 4
• 2-6
• 2 to 6

Notes :

• The distances from each origin atom will only be displayed if the number of destination atoms (coordination number) lies within the range n to k where k >= n. If only one number n is given it is assumed that k=n.
• In calculating the coordination, only those atoms selected by the required Distance Select and either the Distance Range or Min. Distance criteria are considered.
• Note that Distance Select should be accelerated by reducing the number of entries to be calculated using other selection criteria, and in particular the Min. Distance criterium.